UV curable polymers have developed into an important coatings research area, in part, because of their environment-friendly chemistry. While coatings based on acrylate chemistry are the dominant technology, the development of non-acrylate UV curable coatings is a growing area of research interest especially in view of the health concerns associated with acrylate chemistry. The major categories in non-acrylate technology include cationic polymerization, thiol-ene systems, and free-radical induced alternating copolymerization. These chemistries exhibit properties that are similar to acrylates with respect to cure times. Low toxicity and, perhaps more importantly, design flexibility are other benefits.
As discussed briefly above, free-radical induced alternating copolymerization is one alternative to acrylate UV curable coating. Free-radical induced alternating copolymerization takes place when an electron-rich vinyl group is mixed with an electron deficient vinyl group. This chemistry is also referred to as donor-acceptor systems. The general features of this type of polymerization are stoichiometric dependence and formation of charge-transfer complexes.
Ablative photodecomposition was discovered when high energy UV lasers were applied to polymers. One of the important applications envisaged for this process was its application as a dry-etching technique in photolithography. Higher resolution and a lower number of processing steps were the expected benefits. However, the use of standard polymers for laser ablation did not deliver the expected results. This, it is believed, is due to the lower sensitivity of polymers at the irradiation wavelength of operation.
In view of this, there is a need for methods and materials which can be used to make polymers that have improved laser ablation properties. The present invention is directed, in part, to meeting this need.